TWI474608B - Optimal phase searching method of sine-wave voltage driving for surface permanent magnet synchronous motor - Google Patents

Description

Optimal phase fine adjustment method for driving voltage of DC brushless motor

The present invention relates to a DC brushless motor technology, and more particularly to an optimum phase trimming method for a DC brushless motor drive voltage.

DC motors are widely used in places where high-precision control is required because of their excellent stability and response, and their linearity between input and output, which allows them to have very good control performance. However, the conventional DC motor structure has the following defects: for example, the brush and the commutator as the rectifying mechanism are mechanical contacts, which are easy to cause wear, sparks, electrical noise, etc. due to sliding, resulting in motor reliability. Reduce and eliminate the need for brush replacement, inspection and maintenance.

The brushless motor replaces the rectification part (brush and commutator) of the traditional DC motor electronically and retains the DC motor for rapid acceleration. The speed is proportional to the applied voltage, and the torque is proportional to the armature current. The advantage is a motor with very good characteristics.

Fig. 1 and Fig. 2 are a cross-sectional view and a structural view of a brushless motor. It can be seen from the figure that the excitation portion of the brushless motor is composed of a permanent magnet on the rotor, and the armature is located on the stator, so that the brush can be used to conduct current. Brushless motors are classified according to the stator winding and can be divided into 2-phase, 3-phase, and 5-equal brushless motors. A 3-phase brushless motor is more common, and its structure is similar to that of a synchronous motor (the phase angles of the three windings of the stator are 120 degrees apart). Therefore its drive The dynamic circuit generally uses a pulse width modulation (PWM) type converter, and a magnetic pole detecting element such as a Hall element or a resolver can obtain a smooth and stable torque, which is often used in situations requiring high speed and high precision control. .

The biggest feature of the DC brushless motor is the relationship of the brushless structure, and in principle no noise is generated. This is not only mechanical noise, but also makes electrical noise not happen. Moreover, because of the non-contact portion, it is easier to manufacture a high-speed rotary motor. However, when driving a DC brushless motor, the Hall signal output by the Hall element is mostly used as the start position of the sine wave, and the Hall element has more or less error with the actual commutation point during installation, and different. Motors have different sizes of errors; therefore, even with the same drive circuit, there are often different effects depending on the motor. A motor with a large tolerance thus consumes more current efficiency and also becomes inferior.

It is an object of the present invention to provide an optimum phase trimming method for driving voltage of a brushless DC motor for adjusting the driving voltage of the motor to an optimum phase.

Another object of the present invention is to provide an optimum phase trimming method for driving voltage of a brushless DC motor to reduce power consumption of the motor.

In view of the above, the present invention provides an optimum phase fine adjustment method for a driving voltage of a DC brushless motor, wherein the DC brushless motor is provided with N Hall elements, and the DC motor is an N-phase DC motor having N a coil, corresponding to the N phase, the first ends of each coil are coupled to each other, and the second end of the first phase coil is respectively coupled to the second end of the first switch of the first phase and a a first end of the first switch of the first phase, wherein the first end of the first switch of the first phase is coupled to a power supply voltage, and the second end of the second switch of the first phase is coupled to a feedback resistor, wherein The natural number and 0<I<=N, the method includes the following steps: when the DC brushless motor drives a stable load, sampling the phase of the DC brushless motor and a corresponding current value thereof, wherein the current value is a current value flowing through the feedback resistor; collecting data of the phase and the current value, searching for a minimum value of the current value of the feedback resistor, and a corresponding offset phase thereof; and adjusting the phase by using the offset phase The on and off times of the first to Nth phase first switches and the first to Nth phase second switches are corrected.

The present invention further provides an optimum phase fine adjustment method for a driving voltage of a DC brushless motor, wherein the DC brushless motor is provided with N Hall elements, and the DC motor is an N-phase DC motor having N coils. Corresponding to the N phase, the first ends of the first coils are coupled to each other, and the second ends of the first phase coils are respectively coupled to the second end of the first phase of the first phase switch and the first end of the first phase of the first phase switch. The first end of the first switch of the first phase is coupled to a power supply voltage, and the second end of the second switch of the first phase is coupled to a feedback resistor, where I is a natural number and 0<I<=N, The method includes the following steps: when the DC brushless motor drives a stable load, sampling the phase of the DC brushless motor and a corresponding current value thereof, wherein the current value is a current value flowing through the feedback resistor; Data of the phase and the current value are calculated by a curve approximation method, and a current quadratic equation of the current value of the feedback resistor and its corresponding phase is calculated; the above quadratic equation is differentiated to obtain a minimum value; Very small Value as an offset The phase adjusts and corrects the on and off times of the first to Nth phase first switches and the first to Nth phase second switches by using the offset phase described above.

According to a preferred method for fine-tuning the driving voltage of the brushless DC motor according to the preferred embodiment of the present invention, the time during which the DC brushless motor drives the stable load is the time during which the DC brushless motor performs phase correction at the factory. In another embodiment, when the user sets the DC brushless motor to a phase correction mode, the DC brushless motor drives the stable load. Additionally, in another embodiment, the curve approximation is a least squares error approximation. In another embodiment, the stable load described above is idling.

The spirit of the present invention is to utilize the collected current value and its corresponding phase value, and to use the relationship between the two to find the phase shift caused by the mounting tolerance of the Hall element. Then, by this phase shift, the phase of the driving voltage of the driving motor is adjusted to find the optimum sinusoidal voltage driving phase so that the current consumed when the motor is driven is minimized.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

Figure 3 is a system circuit diagram of a three-phase six-step DC brushless motor. Referring to FIG. 3, the three-phase six-step DC brushless motor includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, a fifth switch Q5, and a sixth switch. Q6, a feedback resistor R_Shunt and a brushless motor, wherein the DC brushless motor includes a first phase line Winding U (U-phase coil), a second phase coil Winding V (V-phase coil) and a third-phase coil Winding W (W-phase coil). 4A, 4B, and 4C are driving voltage waveform diagrams of the three-phase six-step DC brushless motor when the Hall element has no mounting tolerance. Please refer to Figure 4A first. Hall U is the Hall signal (U phase Hall signal), Driving Voltage is the driving voltage, and Phase Bemf is the back electromotive force. From the above waveforms, it can be seen that when the Hall element has no mounting tolerance, the back electromotive force Phase Bemf has no phase difference with the driving voltage Driving Voltage and the Hall signal Hall U. Next, please refer to Figure 4B. Hall U is the Hall signal, and Phase Current is the drive current. It can also be seen from the figure that when the Hall element has no mounting tolerance, the drive current Phase Current and the Hall signal Hall U are not. Phase difference. Next, please refer to Figure 4C, Hall U is the Hall signal, and Shunt Current is the feedback current. When the Hall element has no mounting tolerance, the feedback current Shunt Current is relatively small, indicating that the virtual power consumed by the motor is small.

5A, 5B, and 5C are driving voltage waveform diagrams of the above-described three-phase six-step DC brushless motor when the counter electromotive force leads the driving voltage by 10 degrees. Please refer to FIG. 5A, FIG. 5B and FIG. 5C at the same time. Hall signal Hall U is in phase with the driving voltage Driving Voltage, but the back electromotive force Phase Bem leads the driving voltage Driving Voltage phase by about 10 due to the mounting tolerance of the Hall element. Degree, causing the feedback current Shunt Current to increase.

6A, 6B, and 6C are respectively the electric angle of 10 degrees behind the driving voltage of the counter electromotive force, and the above three-phase six-step DC brushless motor Drive voltage waveform diagram. Please refer to FIG. 6A, FIG. 6B and FIG. 6C at the same time. For the same reason, the Hall signal Hall U is in phase with the driving voltage Driving Voltage, but the back electromotive force Phase Bem is behind the driving voltage Driving due to the mounting tolerance of the Hall element. The Voltage phase is about 10 degrees, causing the feedback current Shunt Current to increase.

FIGS. 7A, 7B, and 7C are driving voltage waveform diagrams of the three-phase six-step DC brushless motor when the counter electromotive force leads the driving voltage by 30 degrees. 8A, 8B, and 8C are driving voltage waveforms of the three-phase six-step DC brushless motor when the back electromotive force is behind the driving voltage by 30 degrees. 5A, 5B, 5C, 6A, 6B, 6C, 7A, 7B, 7C, 8A, 8B, and 8C It can be seen that as long as the Hall element has mounting tolerances, causing a phase difference between the back electromotive force and the driving voltage, the feedback current is increased, and the power consumption of the DC brushless motor is caused, so that the efficiency of the DC brushless motor is lowered.

[First Embodiment]

From the above, the Hall element has more or less error with the actual commutation point during installation, resulting in power consumption of the DC brushless motor, which makes the efficiency of the DC brushless motor low. Therefore, the optimal phase fine adjustment method for the driving voltage of the DC brushless motor is proposed. Fig. 9 is a flow chart showing an optimum phase fine adjustment method of the driving voltage of the brushless DC motor. Please refer to Figure 9, this method includes the following steps:

Step S901: Start.

Step S902: setting the DC brushless motor to drive a stable load. In general, the load must be stabilized and the results of the sampling will be accurate before starting the phase correction. Usually for the sake of convenience, this DC brushless motor is usually set to no load.

Step S903: sampling the phase of the DC brushless motor and a corresponding current value thereof. In general, this step samples the current flowing through the feedback resistor. Since the current flowing through the feedback resistor is closely related to the power consumption and efficiency of the motor, step S903 samples the current and records the relationship between the current value flowing through the feedback resistor and the phase of the driving voltage.

Step S904: Searching for the relationship between the current value of the recorded feedback resistor and the phase of the driving voltage to find the minimum value of the current value of the feedback resistor and its corresponding offset phase. Please refer to Figure 10, which is a diagram showing the relationship between the driving voltage after sampling and the angle of the appliance. As shown in Fig. 10, when the angle of the appliance is about 10 degrees, the current is the minimum value, so the offset phase is set at about 10 degrees.

Step S905: Adjust and correct the on and off times of the first to Nth phase first switches and the first to Nth phase second switches by using the offset phase. In this way, the phase can be advanced by 10 degrees to improve the efficiency of the DC brushless motor and reduce power consumption.

Step S906: End.

[Second embodiment]

The above embodiment uses a method of collecting data to find the minimum value. The disadvantage of this method is that when the number of samples is not enough or is not accurate enough, there will still be some The micro error, in this embodiment, the phase correction is performed in another way, please refer to Fig. 11, which is a flow chart of the optimum phase fine adjustment method of the driving voltage of the brushless DC motor. This method includes the following steps:

Step S1101: Start.

Step S1102: The DC brushless motor is set to drive a stable load. In general, the load must be stabilized and the results of the sampling will be accurate before starting the phase correction. Usually for the sake of convenience, this DC brushless motor is usually set to no load.

Step S1103: sampling the phase of the DC brushless motor and a corresponding current value thereof. In general, this step samples the current flowing through the feedback resistor. Since the current flowing through the feedback resistor is closely related to the power consumption and efficiency of the motor, step S1103 samples the current and records the relationship between the current value flowing through the feedback resistor and the phase of the driving voltage.

Step S1104: Perform a curve approximation on the relationship between the current value of the feedback resistor and the phase of the driving voltage, and calculate a current value of the feedback resistor and a phase quadratic equation corresponding thereto.

Step S1105: Differentiating the above-described quadratic equation to obtain a minimum value. Figure 12 is a graph of a quadratic equation using the relationship between the driving voltage and the angle of the appliance. Referring to Fig. 12, a quadratic quadratic equation 1201 can be obtained by curve approximation as follows: y = 0.0166 x ² +0.4561 x +8.1282.........EQ1

In order to get the minimum value, the curve is differentiated dy/dx =0.0332 x +0.4561.........EQ2

Another dy/dx =0 can get x = -13.74

It can be known that the Hall signal is just behind the electrical angle of 13.74 degrees. Therefore, when the electrical angle is 13.74 degrees, the current is the minimum, so the offset phase is set at 13.74 degrees.

Step S1106: Adjust and correct the on and off times of the first to Nth phase first switches and the first to Nth phase second switches by using the offset phase. In this way, the phase can be advanced by 13.74 degrees to improve the efficiency of the DC brushless motor and reduce power consumption.

Step S1107: End.

The methods of the first embodiment and the second embodiment described above can perform optimal phase fine adjustment before the motor leaves the factory, or perform optimal phase fine adjustment on the line when the user is in use. It is more important to note that the above-mentioned optimal phase fine-tuning method must have a relatively accurate phase adjusted under a stable load. The most convenient situation is generally empty.

In summary, the spirit of the present invention is to utilize the collected current value and its corresponding phase value, and use the relationship between the two to find the phase shift caused by the mounting tolerance of the Hall element. Then, by this phase shift, the phase of the driving voltage of the driving motor is adjusted to find the optimum sinusoidal voltage driving phase so that the current consumed when the motor is driven is minimized.

The specific embodiments of the present invention are intended to be illustrative only and not to limit the invention to the above embodiments, without departing from the spirit of the invention and the following claims. The scope of the invention and the various changes made are within the scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

S901~S906‧‧‧ steps of the first embodiment of the present invention

S1101~S1107‧‧‧ steps of the second embodiment of the invention

Figure 1 is a cross-sectional view of a prior art brushless motor.

Fig. 2 is a structural view of a prior art brushless motor.

Figure 3 is a system circuit diagram of a three-phase six-step DC brushless motor.

4A, 4B, and 4C are driving voltage waveform diagrams of the three-phase six-step DC brushless motor when the Hall element has no mounting tolerance.

5A, 5B, and 5C are driving voltage waveform diagrams of the above-described three-phase six-step DC brushless motor when the counter electromotive force leads the driving voltage by 10 degrees.

6A, 6B, and 6C are driving voltage waveform diagrams of the above-described three-phase six-step DC brushless motor when the counter electromotive force is behind the driving voltage by 10 degrees.

FIGS. 7A, 7B, and 7C are driving voltage waveform diagrams of the three-phase six-step DC brushless motor when the counter electromotive force leads the driving voltage by 30 degrees.

8A, 8B, and 8C are driving voltage waveforms of the three-phase six-step DC brushless motor when the back electromotive force is behind the driving voltage by 30 degrees.

Fig. 9 is a flow chart showing an optimum phase fine adjustment method of the driving voltage of the brushless DC motor.

Figure 10 is a graph showing the relationship between the driving voltage after sampling and the angle of the appliance.

Figure 11 is the best phase trimming of the drive voltage of a DC brushless motor. Flow chart of the method.

Figure 12 is a graph of a quadratic equation using the relationship between the driving voltage and the angle of the appliance.

S901~S906‧‧‧ steps of the first embodiment of the present invention

Claims (9)

An optimum phase fine adjustment method for driving voltage of a DC brushless motor, wherein the DC brushless motor is provided with N Hall elements, and the DC motor is an N-phase DC motor having N coils corresponding to the N phase, The first ends of the first phase coils are coupled to each other, and the second ends of the first phase coils are respectively coupled to a second end of the first phase first switch and a first end of the first phase second switch, wherein the first end The first end of the first switch of the I phase is coupled to a power supply voltage, and the second end of the second switch of the first phase is coupled to a feedback resistor, where I is a natural number and 0<I<=N, the method includes : when the DC brushless motor drives a stable load, sampling the phase of the DC brushless motor and a corresponding current value thereof, wherein the current value is a current value flowing through the feedback resistor; collecting the phase and the current The value of the data, and search for the minimum value of the current value of the feedback resistor, and its corresponding offset phase; and use the offset phase to adjust and correct the first to the Nth phase first switch and the first to the first The conduction and cut-off time of the N-phase second switch. An optimum phase fine adjustment method for driving voltage of a DC brushless motor as recited in claim 1, wherein the time during which the DC brushless motor drives the stable load is a time during which the DC brushless motor performs phase correction at the factory. The best phase fine adjustment method for the driving voltage of the DC brushless motor as described in the first paragraph of the patent application, wherein one user has no DC When the brush motor is set to a phase correction mode, the DC brushless motor drives a stable load and starts sampling the phase of the DC brushless motor and a corresponding current value thereof. An optimum phase fine adjustment method for a driving voltage of a DC brushless motor as recited in claim 1, wherein the stable load is idling. An optimum phase fine adjustment method for driving voltage of a DC brushless motor, wherein the DC brushless motor is provided with N Hall elements, and the DC motor is an N-phase DC motor having N coils corresponding to the N phase, The first ends of the first phase coils are coupled to each other, and the second ends of the first phase coils are respectively coupled to a second end of the first phase first switch and a first end of the first phase second switch, wherein the first end The first end of the first switch of the I phase is coupled to a power supply voltage, and the second end of the second switch of the first phase is coupled to a feedback resistor, where I is a natural number and 0<I<=N, the method includes : when the DC brushless motor drives a stable load, sampling the phase of the DC brushless motor and a corresponding current value thereof, wherein the current value is a current value flowing through the feedback resistor; collecting the phase and the current The value data is calculated by a curve approximation method, and the current value of the feedback resistor and its corresponding phase quadratic equation are calculated; the quadratic equation is differentiated to obtain a minimum value; and the minimum value is used as a bias Shift phase, use the offset phase, adjust Correction of the first to Nth phase first switches and the first to Nth phase second switches Turn-on and deadline. An optimum phase fine adjustment method for driving voltage of a DC brushless motor as recited in claim 5, wherein the time during which the DC brushless motor drives the stable load is a time during which the DC brushless motor performs phase correction at the factory. The optimum phase fine adjustment method of the driving voltage of the DC brushless motor described in claim 5, wherein the DC brushless motor drives the stabilization when the DC brushless motor is set to a phase correction mode. Load, and start sampling the phase of the DC brushless motor and its corresponding current value. An optimum phase fine adjustment method for a driving voltage of a DC brushless motor as recited in claim 5, wherein the curve approximation is a least square error approximation. An optimum phase fine adjustment method for a driving voltage of a DC brushless motor as recited in claim 5, wherein the stable load is idling.